Method for monitoring and controlling locomotives

ABSTRACT

The present invention is directed to a locomotive comprising energy storage units, such as batteries, a prime energy source, such as a diesel engine, and an energy conversion device, such as a generator. The locomotive comprises one or more of the following features: a separate chopper circuit for each traction motor; energy storage units that can be switched from parallel to series electrical connections, an fluid-activated anti-lock brake system, a controller operable to control separately and independently each axle/traction motor, and a controller operable to control automatically a speed of the locomotive. The present invention includes an integrated system for monitoring, controlling and optimizing an electrically powered locomotive using a combination of sensors and software to provide feedback that optimizes power train efficiency and individual drive axle performance for a locomotive that utilizes one of several possible electrical energy storage systems to provide the tractive power. The net result is a locomotive that has an integrated system of control over all aspects of the locomotive power train including control over individual drive axles, especially during acceleration, braking and non-synchronous wheel slip.

CROSS REFERENCE TO RELATED APPLICATION

Cross-reference is made to U.S. application, Ser. No.______, filed Aug.26, 2003, entitled “A Method for Monitoring and Controlling TractionMotors in Locomotives,” to Donley, et al., which contains relatedsubject matter and is incorporated herein by this reference.

FIELD OF INVENTION

The present invention relates generally to a method and system foroptimizing the performance and maintenance profile of a locomotive byexercising control over various aspects of the drive train includingcontrol over individual drive axles.

BACKGROUND OF THE INVENTION

Existing railroad locomotives are typically powered by diesel electricengines in which a diesel motor drives an electric generator to produceelectric power to drive electric motors which in turn drive the drivewheels of the locomotive. The present inventor has disclosed the use ofa gas turbine engine fueled by compressed natural gas in substitutionfor the traditional diesel engine in his U.S. Pat. No. 5,129,328 issuedJul. 14, 1992, and as a booster unit for the diesel engine in his U.S.Pat. No. 4,900,944 issued Feb. 13, 1990, both of which are incorporatedherein by reference.

The use of energy storage batteries in combination with a generator isknown for automobiles, buses and other road and highway vehicles. Suchhybrid engines for vehicles are advantageous due to their increased fuelefficiency and reduced pollution. In those applications, it is importantto minimize the weight of the batteries to maintain fuel efficiency.Electric batteries have been used to store electric power to driveelectric locomotives as, for example, disclosed by Manns in U.S. Pat.No. 1,377,087 issued May 3, 1921 which is incorporated herein byreference. In Manns, three standard diesel engines are used to drivegenerators to charge the storage batteries. Such a system has notachieved commercial acceptance over existing diesel electric locomotivesdue to the added cost and complexity of providing multiple dieselengines in addition to the storage batteries.

The present inventor has also disclosed the use of a battery poweredlocomotive which has a ratio of energy storage capacity to chargingpower in the range of 6 to 40 hours in his U.S. Pat. No. 6,308,639issued Oct. 30, 2001 which is also incorporated herein by reference.

The present inventor has also disclosed the use of individual choppercircuits associated with individual drive axles in his copending U.S.patent application Ser. No. 10,083,587 filed on Feb. 26, 2002.

There remains a need for a fuel-efficient locomotive which uses acombination of a small fuel-powered generator, a substantial energystorage capacity, and control systems that regulates and maintains thepower train at maximum fuel efficiency and minimizes maintenance. Suchcontrol systems would also allow greater command over individual driveaxles to help alleviate undesirable conditions such as non-synchronouswheel slippage and wheel locking.

SUMMARY OF THE INVENTION

These and other needs are addressed by the various embodiments andconfigurations of the present invention. The present invention isdirected generally to an integrated method for monitoring, controlling,and/or optimizing an electrically powered locomotive.

In a first embodiment, each axle assembly, which is typically an axle, atraction motor, and two wheels, is monitored and controlledindependently using one or more sensors and a control feedback loop. Thelocomotive typically includes a plurality of axle assemblies, a primaryenergy source, an energy storage unit, and an energy conversion deviceto convert the energy output by the primary energy source into a formsuitable for storage in the energy storage unit.

For example, in one configuration an individual chopper circuit isprovided for each traction motor. Each chopper circuit typicallyincludes a drive switch, a free-wheeling bypass, which further includesa free-wheeling gate, and a filter to absorb voltage transients andsmooth motor current ripples during switching. During any selected timeinterval, each chopper circuit is either in the driven or free-wheelingmode. In the driven mode, the drive switch is conducting and a powerpulse is provided to the traction motor. In the free-wheeling mode, thedrive switch is non-conducting and the power pulse circulates throughthe free-wheeling bypass circuit. By time sequencing the power pulses toindividual traction motors, the current draw on the energy storagesystem can be minimized over a significant portion of the operatingrange since instantaneous current requirements from individual motorsare not additive. This independence of individual current requirementscan have the positive effect of reducing both the impedance seen by theenergy storage unit and the internal resistive losses sustained in theenergy storage unit. The flexibility of individually controlling powerto the traction motors can be an efficient and effective approach tocorrecting non-synchronous wheel slip. The simplified circuit affords astraightforward means of smoothly removing and then restoring power to aslipping wheel while maintaining the pre-slip level of power to thewheels not experiencing slip. This can have the advantage ofsignificantly reducing the power requirements and tread wear typicallyexperienced with incidents of non-synchronous wheel slip.

In yet another example, the revolutions per minute of each axle aremonitored to detect wheel slip during locomotive acceleration or wheellock during braking. As will be appreciated, wheel lock can occur whenbrakes are applied and are either slow or unable to release uponcommand. When the revolutions per minute exceed a selected threshold,the controller assumes that the wheels on the axle are slipping andcontrols power to the respective traction motor as set forth above. Whenthe revolutions per minute are at or near zero when the brakes have beenapplied or after brakes have been released, the controller assumes, ifother motion detectors such as, for example, a doppler radar systemindicates locomotive movement, that the brakes are locked andselectively applies a pressurized fluid, such as air, to afluid-activated brake release. The pressurized fluid is forced throughports in the brake shoe (or pad in the case of disc brakes) and againstthe braking surface to forcibly release the brake shoe or pad from thebraking surface.

In yet another embodiment, a controller controls an excitation circuitto the energy conversion device to control the load on the primaryenergy source. There are two methodologies for controlling theexcitation circuit. First, when a first predetermined set point isexceeded by a first monitored parameter, the excitation current isincreased and, when a second predetermined set point exceeds the firstmonitored parameter, the excitation current is decreased. The firstmonitored parameter is revolutions per minute of a mechanical componentof the prime energy source. Second, when the first predetermined setpoint is exceeded by a second monitored parameter, the excitationcurrent is decreased and, when the second predetermined set pointexceeds the second monitored parameter, the excitation current isincreased. The second monitored parameter is the output power of theenergy conversion device. In this manner, the primary energy source,when operating, can be reliably maintained at or near a peak fuelefficiency, maximum torque, maximum power or any other desired engineoperating condition.

In yet another embodiment, a controller is configured to providereliable speed control for the locomotive. The velocity of thelocomotive may be controlled by two primary techniques. In a firsttechnique, a substantially constant power is maintained across each ofthe plurality of traction motors. As will be appreciated, the power isrelated to the specified velocity. In a second technique, therevolutions per minute of each of the plurality of axles are maintainedat a rate related to the specified velocity. In these technique, theindividual monitoring of the power and/or revolutions per minute of eachaxle assembly can permit different powers pulses to be applied acrosseach traction motor. Such selective power pulse application can takeinto account operational differences among the axle assemblies, such asdifferently sized wheels, traction motors of differing efficiencies, andthe like.

In another embodiment, the energy storage unit of the locomotive isconfigured as a bank of capacitors which store at least most of theelectrical energy. A pulse forming network can be provided to convertthe output of the capacitors to a form acceptable to the tractionmotors. This embodiment would be preferred if a bank of capacitors havea higher energy density than a battery pack of comparable storagecapacity.

In a preferred embodiment, a controller unit and system of sensors isused to monitor, synchronize and optimize the operation of thelocomotive drive train as well as the individual drive axles especiallyduring acceleration and braking. The controller also provides thelocomotive operator with information through a system of performancedata and warnings that allow the operator to manually override variousfunctions in an emergency. The information and warnings may be providedby conventional means such as warning lights and bells and the like, orby these conventional means supplemented by and by a computer consolethat can access a variety of control and informational screens.

These and other advantages will be apparent from the disclosure of theinvention(s) contained herein.

The above-described embodiments and configurations are neither completenor exhaustive. As will be appreciated, other embodiments of theinvention are possible utilizing, alone or in combination, one or moreof the features set forth above or described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the principal elements of the preferred embodiment.

FIG. 2 shows a schematic representation of sensor locations formonitoring the power, charging and braking systems of a battery-poweredlocomotive.

FIG. 3 shows an electrical schematic of a motor generator with exciterfield control.

FIG. 4 is a schematic representation of the elements of an energystorage battery pack.

FIG. 5 shows a schematic of a battery pack with all racks connected in aseries configuration.

FIG. 6 shows a schematic of a battery pack with some of the racksconnected in a parallel and some in series.

FIG. 7 shows a schematic of a battery pack with some of the racksconnected in a parallel and some in series and reconfigurable for addingmore output power.

FIG. 8 shows a schematic of a typical chopper circuit illustrating thefree-wheeling current path.

FIG. 9 shows an electrical schematic of a battery energy storage systempowering four DC traction motors.

FIG. 10 shows a sequence of non-overlapping short power pulses as mightbe provided by the circuit of FIG. 9.

FIG. 11 shows a sequence of power pulses that do not overlap but also donot have any intervening space as might be provided by the circuit ofFIG. 9.

FIG. 12 shows a sequence of power pulses that have some overlap as mightbe provided by the circuit of FIG. 9.

FIG. 13 shows a sequence of power pulses that have substantial overlapas might be provided by the circuit of FIG. 9.

FIG. 14 shows a sequence of power pulses that have continuous overlap asmight be provided by the circuit of FIG. 9.

FIG. 15 shows an electrical schematic of a capacitor energy storagesystem powering four DC traction motors.

FIG. 16 shows a schematic of a rail truck assembly illustrating thelocation of air brake cylinders.

FIG. 17 shows an isometric view of a typical rail air brake system.

FIG. 18 shows a schematic drawing of a brake shoe with provisions for anair-actuated release mechanism.

FIG. 19 shows a schematic of how an air brake release system mightoperate with a wheel tread brake.

FIG. 20 shows a schematic of how an air brake release system mightoperate with a disc brake.

FIG. 21 shows a flow diagram for the logic for main power control of abattery-powered locomotive.

FIG. 22 shows a flow diagram for the logic for a fuel-efficient chargingcontrol for the charging apparatus of a battery-powered locomotive.

FIG. 23 shows a flow diagram for the logic for an air-braking and wheellock release system for use on rail cars and locomotives.

FIG. 24 shows a flow diagram for the touch screen information andcontrol system.

FIG. 25 shows an example of a main menu screen.

FIG. 26 shows an example of a traction motor summary screen.

FIG. 27 shows an example of an individual traction motor screen.

FIG. 28 shows an example of a battery status screen.

FIG. 29 shows an example of a battery monitoring system screen.

FIG. 30 shows an example of a control tools screen.

FIG. 31 shows an example of an alarm history screen.

FIG. 32 shows an example of a digital input monitor screen.

FIG. 33 shows an example of an output monitor screen.

FIG. 34 shows an example of a warnings screen.

FIG. 35 shows an example of a derate and shutdown screen.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention discloses an integrated method for monitoring,controlling and optimizing an electrically powered locomotive using acombination of sensors and software to provide feedback that optimizespower train efficiency and individual drive axle performance for alocomotive that utilizes one of several possible electrical energystorage systems to provide the tractive power. A drive axle is comprisedof a DC traction motor, an axle and two wheels. The locomotive includesat least two drive axles and can typically include as many as 8 driveaxles. In addition to utilizing an electrical energy storage system andindividual chopper circuits for each of a subset of drive axles (whichtypically is an individual chopper circuit for each drive axle), thepresent invention incorporates a comprehensive logic and software systemto monitor, control and optimize the flow of power in the locomotive.This system includes a method of load control for the prime energysource; a method of releasing locked wheels; and a method of accuratelycontrolling the speed of the locomotive in the low speed range. The netresult is a locomotive that has an integrated system of control over allaspects of the locomotive power train including control over individualdrive axles, especially during acceleration and braking.

The locomotive power train generally includes the following principalelements as shown in FIG. 1. A prime energy source 1001 provides thebasic energy to the system. The prime energy source 1001 drives anapparatus or device 1002 for converting mechanical energy of the primeenergy source to a direct current (“DC”) output charging source. A primeenergy storage unit or device 1003 stores electrical energy delivered bythe conversion apparatus 1002 and provides most of the power for thetraction motors. The locomotive may also include a number of auxiliarysystems represented here as a single element 1004. These include, forexample, auxiliary compressors (not shown), auxiliary power supplies(not shown) of various voltages, heating and cooling systems (notshown), and lighting and auxiliary control equipment (not shown). In thepresent invention, power is supplied to these auxiliary systems 1004, asrequired, by the main energy storage system 1003 since the chargingsource 1002 may or may not be operating.

The locomotive may have a plurality of axle assemblies 1005, each ofwhich is comprised of an axle 1006, wheels 1007, a traction motor 1008and an air-brake 1009. The air-brake 1009 may be a conventional disc ortread type rail braking system or it may be a conventional brakingsystem that includes an air-activated brake release system used inwheel-lock situations, such as described in FIG. 18. In the presentinvention, each axle assembly 1005 with a traction motor 1008 has achopper circuit 1010 associated with it. Each chopper circuit 1010derives its power from the energy storage device 1003 and allocates andconfigures the power flow from the energy storage unit 1003 to at leasttwo of, and typically each of, the DC traction motors 1008.

In the present invention, a locomotive master chopper control system1015 and individual axle chopper circuits 1010 provide a method ofcontrolling power provided from the energy storage unit 1003 to thedirect current traction motors 1008. This method generally includes thesteps of: a) determining the power requirement for each motor 1008 ateach of a number of discrete, successive time intervals; b) determiningthe necessary effective power pulse width, amplitude and spacing toachieve the desired power for each motor 1008 during a selected timeinterval; c) sequentially pulsing power to at least some of the motors1008 during the selected or a subsequent time interval for a duration(or length of time) necessary to achieve the power requirement at eachtime interval.

The individual chopper circuits 1010 receive timing and powerinstructions from the locomotive master chopper control system 1015which includes a master clock 1051 (an integrated circuit that generatesa series of pulses) and pulse sequencer 1052 (an integrated circuit thatsequences the pulses into uniform periods for purposes of the pulsewidth regions for each motor). Each chopper circuit 1010 includes atleast its own: pulse width modulator 1053 (provides ‘clipped’ triangularwaveforms that result in the creation of a series of pulses, which isused essentially to toggle the power switch devices on and off accordingto the pulses); and drive switch 1054 (insulated gate bipolartransistors, abbreviated as IGBTs, that are switching devices capable ofsequentially ‘pulsing’ the power source to the different motors at avery fast rate). A latching circuit (not shown), can also be providedthat is set so that after the IGBT has failed to fully saturate or afault current has been detected, it will interrupt the drive to theIGBT. This forces the IGBT off and prevents the IGBT from operating intoa short circuit. The latching circuit can be provided by an electroniccircuit board or by software logic associated with logic unit 1011described below.

All of the principal elements of the locomotive are monitored,co-ordinated and controlled by a such as, for example, a ProgrammableLogic Circuit (“PLC”), a micro-controller, or an industrial computer.The logic unit 1011 includes: a ramping function 1061 (logic to ramprequested throttle level at a rate that is reasonable for thelocomotive); a power dispatch logic 1062 (central logic that evaluatesany pertinent derate conditions, any wheel slip, as well as therequested throttle level, to determine the appropriate power level to besent to the pulse width modulation module 1053); an detection scalingfunction 1063 (logic for determining non-optimal performance, such aswheel slip. Power reduction to individual motors can be put in place inthe case of differential wheel slip and overall power is reduced in thecase of synchronous wheel slip); a derate evaluation logic 1064 (logicto reduce the power demand below that requested by the operator forprotection of equipment. This could include reducing power in caseequipment is at risk of overheating or currents climb close to equipmentdesign limits); a brake control logic 1065 (control of the air brakesystem including individual axle wheel lock release); and a generator1002 load control logic 1066 (control of the generator 1002 excitationfield to maintain the prime energy source 1001 at approximately peakfuel efficiency or other desired condition). The logic unit 1011receives the information from an operator input device 1071 whichincludes a throttle setting 1072 and a speed setting 1073. The throttle1072 is typically a throttle notch between idle and eight positions butalso could be an electronic device, such as an infinitely variablecontrol or a touch screen. The speed setting 1073 is typically arheostat motor voltage control but also could be an electronic device,such as an infinitely variable control or a touch screen. The logic unit1011 also receives the input information on the status of variouscomponents of the system from several sensing devices described below inFIG. 2. As discussed above, the logic device 1011 processes all theinput information and sends out instructions to co-ordinate theoperation of: the prime energy source; the DC conversion apparatus; thecharging and discharging of the energy storage unit; the DC tractionmotor electrical controllers; the DC traction motors; and the brakingsystem on the individual axle assemblies 1005. The continuous lines 1081connecting various elements represent physical connections and thedashed lines 1082 connecting various elements represent simplifiedelectrical control and informational linkages. It should be noted thatthe control and informational linkages shown apply to all the axleassemblies 1005, even though the connections are shown only to the firstassembly.

The prime energy source can be any suitable power or energy source suchas for example a reciprocating diesel engine, a gas turbine engine, asmall diesel reciprocating engine, a microturbine, a fuel cell.Alternately, prime energy can be provided by an external source such asoverhead electrical trolley wires or directly plugging into a utilitygrid. The prime energy source 1001 is preferably a high-efficiencyreciprocating diesel engine with a preferred power rating approximatelyin the range of about 25 to 250 kW. With reference to the energy storageunit 1003, the preferred range of the ratio of energy storage capacityto charging power of the generator is in the range of about 6 hours to40 hours. When charging is required, it is more preferable for the primeenergy source 1001 to be operated at or near its peak fuel efficiencyrating which is preferably in the range of approximately 12 to 16 kwhper gallon of fuel for a small diesel engine. It may also be preferablefor the prime energy source 1001 to be operated at or near its peaktorque or power rating under certain circumstances and these operatingregimes would require different set points. Otherwise, when the energyof the energy storage unit 1003 is at its full rated storage capacity(as determined, for example, by an upper voltage set point in the caseof a battery pack), the prime energy source 1001 is preferably turnedoff. The prime energy source 1001 may also be turned off when, forexample, the locomotive is operating in a confined space, such, as forexample, a locomotive maintenance shed.

The conversion apparatus 1002 typically converts mechanical energy formthe prime energy source 1001 to direct current (DC) electrical energyand the conversion is preferably effected by an alternator which outputsrectified DC power to an energy storage device 1003. The alternator ispreferably driven by the prime energy source. The charging generator1002 is preferably an alternator that operates in the approximate therange of about 50 to 75 Hertz. The alternator is driven by the primeenergy source and may contain a means for converting alternating (“AC”)electrical power to direct current (“DC”) electrical power. Thealternator power output is preferably controlled by varying theexcitation current to the alternator field coils.

The control of the power output of the DC charging system 1002 to theenergy storage unit 1003 can be accomplished, for example, by varyingthe excitation current provided to the alternator 1002 to maintain an atleast substantially constant power output to the energy storage unit1003, while appearing as an approximately constant load to the primeenergy source 1001. There are typically at least two techniques ofcontrolling the output of the charging generator 1002 to effect loadcontrol for the diesel engine. In a first technique, the RPMs of thediesel engine are monitored such as, for example, by a tachometer andthe RPMs are maintained within a range which is defined by upper andlower RPM set points. This range is selected for maximum fuel efficiencyof the prime energy source. If the RPMs fall below the selected range(indicating a heavy load on the engine), then the excitation current tothe alternator can be reduced to reduce the power output of thealternator until the engine RPMs are restored to within the desiredrange. If the RPMs rise above the selected range (indicating a lightload on the engine), then the excitation current to the alternator canbe increased to increase the power output of the alternator until theengine RPMs are restored to within the desired range. In a secondtechnique, the DC output power of the alternator is monitored asdetermined by the product of the measured output volts and amperes. Ifthe output power falls below the lower set point of the selected outputpower range, then the excitation current to the alternator can beincreased to restore the power output to within the desired range. Ifthe output power rises above the upper set point of the selected range(presenting a heavy load to the engine), then the excitation current tothe alternator can be decreased to reduce the power output to within thedesired range. In this technique, the RPMs of the engine can also bemonitored to ensure that the RPMs stay within the range selected formaximum fuel efficiency. If they fall outside the selected range, thenthe excitation current to the alternator can be further modified tobring the engine RPMs back into the desired range.

In the event that prime energy is provided by an external source such asoverhead trolley wires or plugging into a utility grid, the chargingsystem 1002 would be replaced by a voltage step-up or step-downapparatus and, if required, a converter from AC to DC power so as toprovide the proper driving voltage to charge the energy storage unit1003.

The electrical controller 1010 for each DC traction motor 1008 ispreferably a chopper circuit such as disclosed in copending U.S. patentapplication Ser. No. 10,083,587, which is incorporated herein by thisreference. The chopper circuit and control system, as applied in thepresent invention, are discussed more fully in FIGS. 8 and 9.

The energy storage unit 1003 may be any other suitable electricalstorage device, such as for example an energy storage capacitor bank, aflywheel generator system of which a homopolar generator is an example.The energy storage unit is typically composed of a plurality ofsubunits, such as batteries and/or storage capacitors. The energystorage unit 1003 is preferably an electrical energy storage batterypack. The electrical generator 1002 provides DC power to the energystorage unit 1003 at an at least substantially constant power, with theoutput voltage being higher than the maximum voltage of the batterypack. The battery pack typically has a maximum voltage, usually input asan upper set point to avoid gas generation or other damage to thebattery cells and a minimum voltage usually input as a lower set pointto avoid seriously diminishing the recharge capacity of the batteryplates. The upper and lower set points define the operational range ofthe battery voltage. The charging generator is preferably always inoperation when the battery voltage is below the lower set point. Thecharging generator is usually in operation when the battery voltage isbelow the upper set point. An exception might be when the locomotive isoperating in, for example, a confined space, where emissions from theprime energy source would be undesirable. The charging generator is mostpreferably not in operation when the battery voltage is above the upperset point.

A new method of setting the upper and lower set points that define theoperational range of the energy storage unit is disclosed. Typically,the upper and lower voltage set points of the energy storage unit areselected by picking an upper voltage and a lower voltage based onexperience. In the new method, the quantity of charge in the energystorage unit is accounted for by continuously (by analogue or digitalsampling) measuring the current flow to and from the energy storage unitand integrating the current time history to determine the state ofcharge in the energy storage unit. The location of the current sensorused to apply this method is shown in FIG. 9. Using this technique, ifthe total charge in the energy storage device falls below the upper setpoint of the selected range, then the charging generator is turned on.If the total charge rises above the upper set point of the selectedrange, then the charging generator is turned off. In the accounting ofcharge in the energy storage unit, a small amount of charge (typically 1or 2% of the total charge) is lost to the system through variousinefficiencies and this loss is estimated and added to the charge totalto maintain an accurate accounting. Either of the above methods may beused separately or in combination to obtain better control over thecharging process for the energy storage device to maintain it within itsoptimum operating range. The same techniques may be used if the energystorage device is a battery pack or a capacitor bank.

As part of its air-braking system, the locomotive may also include asystem 1009 for releasing wheels that become locked during air braking.This wheel release system is discussed more fully in FIG. 18.

To provide the information necessary to synchronize the operation of thevarious components of the locomotive drive train, including, ifnecessary, the operation of individual axles, an appropriate placementof sensors monitors and measures a plurality of parameters asillustrated by FIG. 2. Here, voltage sensors are represented by solidcircles; current sensors by a solid square “C” symbol; temperaturesensors by a solid rectangle; rotary speed sensors by a solid trianglewith vertex pointing up; and pressure sensors by a solid triangle withvertex pointing down. Voltage sensors include voltmeters, other commonvoltage transducers or voltage sensing devices; current sensors includecurrent-sensing resistors, Hall current sensors, current-sensingtransformers, current transducers, Rogowski coils or other commoncurrent measuring devices; rotary speed sensors include tachometers,axle alternators and the like; temperature sensors includethermocouples, thermistors, semi-conductors or other common temperaturemeasuring devices and; pressure sensors include pressure transducers,pressure gages or other common pressure measuring devices. Withreference to FIG. 2, the operating characteristics of the prime energysource 2001 such as, for example, the revolutions per minute (RPMs) ofan internal combustion engine are measured by a first rotary speedsensor 2012; engine temperature by a first temperature sensor 2022 andengine oil pressure by first pressure sensor 2023. The RPMs of the primeenergy source 2001 can also be determined from monitoring the powerfrequency of the conversion device 2002 (as indicated in FIG. 28). Thefield excitation current for the conversion device 2002 is sensed by afirst current sensor 2024 and the temperature of the conversion device2002 is measured by a second temperature sensor 2025. The DC outputvoltage and current are measured for the conversion device 2002, by afirst voltage sensor 2026 and second current sensor 2027. The voltage atseveral locations of the energy storage unit 2003 may be measured usingadditional voltage sensors 2031 and the temperature at several locationsof the energy storage unit 2003 may be measured using additionaltemperature sensors 2032. In addition, the output voltage and currentare measured for the energy storage unit 2003 by a second voltage sensor2033 and third current sensor 2034. The current to each IGBT 2028 on theindividual chopper circuits 2007 are measured by additional currentsensors 2035. The current to each traction motor 2004 is measured byadditional current sensors 2041; the voltage across all or a portion ofeach traction motor 2004 maybe measured by additional voltage sensors2042; and the temperature the voltage representative of each eachtraction motor 2004 may be measured by additional temperature sensors2043. The rotational speed of a plurality of, and typically each, driveaxle 2005 of the locomotive is measured by additional rotary speedsensors 2051. The air pressure in various locations of the locomotivebraking system 2006, including locations where wheel release devices maybe used, are monitored by additional pressure sensors 2061 and thetemperature representative of the brake shoes 2009 may be measured byadditional temperature sensors 2062. The locomotive will typically alsohave a doppler radar detector (not shown) that can independentlydetermine locomotive speed. This system provides an indication oflocomotive speed independent of the axle rotary speed sensors 2051 whichcannot properly indicate locomotive speed when there is a synchronouswheel slip or synchronous wheel locking condition.

An example of a charging generator circuit is shown in FIG. 3 whichshows an exciter coil that can be independently controlled. A stator3001 generates an alternating current which is rectified by power diodes3002. The rectified power is then fed to the prime energy storage source3003 shown here as a storage battery. The rectified power is alsoprovided to various auxiliary systems (not shown) such as for exampleblower and fan motors, lighting and compressors and the like. The outputof the stator 3001 is controlled by an independently controlled excitercoil 3004. The output power to the energy storage source 3003 ismonitored by a current transducer 3005 and a voltage sensor 3006. Thegenerator excitation board 3007 receives its inputs from a computercontrol system via path 3008 or, in an emergency (such as from detectionof an anomalously high voltage output from the generator, for example),from path 3009 originating from the voltage sensed across the stator3001. In the case of such an emergency, the excitation board 3007 hasthe ability to override the control of the main logic controller anddirectly reduce the current to the excitation field coil 3004.

Referring to FIG. 1, the preferred energy storage unit 1003 is a batterypack. The battery pack may be divided into a plurality of racks. Theracks mechanically and removably house the individual battery units tofacilitate maintenance and replacement. The racks contain a plurality ofindividual battery units or other types of energy storage subunits, suchas capacitors. The battery units are each comprised of a set number ofcells. The preferred cells are those of a lead-acid type which has anelectrochemical potential of about 2.13 volts, the highest currentlyavailable in rechargeable battery chemistry. The definition of thesedivisions are illustrated in FIGS. 4 a, b and c which are a schematicrepresentation of the elements of an energy storage battery pack. InFIG. 4 a, a battery unit 4001 is comprised of individual cells 4002, apositive terminal 4003 and a negative terminal 4004. The number of cells4002 is preferably in the range of 1 to 10 and most preferably in therange of 1 to 6. The fewer cells 4002, the easier it may be to replacebattery units that become degraded or fail. As shown in FIG. 4 b,battery units 4006 may be assembled together in a battery rack 4005. Thebattery rack 4005 is typically an assemblage of a convenient number ofbattery units 4006 that allow for easy maintenance or assembly intogroups that are connected in series or in parallel. The number ofbattery units 4006 in a battery rack 4005 is preferably in the range of2 to 50 and more preferably in the range of 4 to 16. Referring to FIG. 4c, battery racks 4008 may be assembled to form a battery pack 4007 whichis largest division considered in the present invention. The number ofbattery racks 4008 in a battery pack 4007 is preferably in the range of4 to 100 and more preferably in the range of 10 to 60. The entirebattery pack 4007 has a a positive terminal 4009 and a negative terminal4010. If a high energy capacitor bank is used as the energy storagemethod, the same definitions may be used with battery units replaced bycapacitors, the battery rack by a capacitor rack and the battery pack bya capacitor bank.

In a preferred embodiment, all of the battery units are connectedelectrically in series so that the capacity rating of the battery pack,expressed in ampere-hours, is the same as the rating of each batteryunit. In this embodiment, the voltage output of the battery pack is thesum of the terminal voltages of all the battery units. This embodiment,shown in FIG. 5, illustrates a schematic of a battery pack in seriesconfiguration. A battery pack 5001 is shown with sixteen battery racks5002 where all the battery units (not shown) in each rack 5002 areconnected in series and all the battery racks are connected in series.In this configuration, all the battery units are in series and thebattery pack 5001 has a positive output terminal 5003 and a negativeoutput terminal 5004. The same configuration may be used with batteryunits replaced by capacitors.

In another embodiment, a number of rack groupings may be connected inparallel. A rack assembly may contain one or more racks. Preferably, therack groupings contain the same number of total battery unitselectrically connected in series, so that the voltage output of eachrack assembly is the same. The preferred number of rack groupings inparallel is in the range of 2 to 6. This configuration increases thecapacity rating of the battery pack to be equal to the rating of eachbattery unit times the number of rack groupings electrically connectedin parallel. In this embodiment, the voltage output of the battery packis the sum of the terminal voltages of all the battery units in any ofthe rack groupings. In this embodiment, the power of the locomotive maybe derived from one or several or all of the rack groupings connectedinto the drive system. It is also possible, in this embodiment, to useindividual rack groupings to control individual or groups of driveaxles. In other words, each individual or subgrouping of drive axles mayhave one or more dedicated individual rack groupings, whereby electricalenergy is provided to each individual or subgrouping of drive axles onlyby a corresponding subset of one or more rack groupings. This embodimentis shown in FIG. 6. The charging system can be configured to charge someor all of the parallel racks. FIG. 6 shows a schematic of a battery packwith some of the racks connected in a parallel and some in series. Eachrack assembly 6001 is comprised of 4 battery racks 6002 and each rackassembly has a positive output terminal 6003 and a negative outputterminal 6004. Each rack assembly 6001 can be used to drive one or moretraction motors (not shown). Alternately, the rack groupings 6001 can beconnected in parallel to drive all the traction motors. In this case theoutput terminals of the battery pack are a positive output terminal 6005and a negative terminal 6006. When all the racks groupings 6001 haveapproximately the same open circuit output voltage at terminals 6004 and6005 and that voltage is sufficient to power the traction motors, anadvantage of parallel racks is to provide greater ampere-hour capacityfor the locomotive. Another advantage is to provide backup power by onlyoperating from one rack of the battery pack. The same configurations maybe used with battery units replaced by capacitors.

In yet another embodiment, a number of rack groupings may be connectedin parallel with the additional capability of providing for some or allof the rack groupings to be electrically switched to be in series withother rack groupings. The purpose of dividing the battery pack in thisway is to provide the ability to rapidly increase the power available todrive the locomotive by, for example, switching automatically ormanually some or all of the rack groupings from parallel to series so asto increase the output voltage of the battery pack. FIGS. 7 a and bshows a schematic of a reconfigurable battery pack for adding moreoutput power. FIG. 7 a shows 3 battery rack groupings 7001, 7002 and7003 connected in parallel with positive output terminal 7004 andnegative output terminal 7005. The voltage output of this battery packconfiguration is approximately the voltage output of each of the rackgroupings. The ampere-hour capacity of this battery pack configurationis the sum of the ampere-hour capacity of each of the rack groupings inparallel. FIG. 7 b shows 2 battery rack groupings 7011 and 7012connected in parallel with positive output terminal 7014 and negativeoutput terminal 7015. The third rack grouping 7003 of FIG. 7 a has beendivided in two. One half has been switched in series to rack grouping7001 to make rack grouping 7011 and the other half has been switched inseries to rack grouping 7002 to make rack grouping 7012. The voltageoutput of this battery pack configuration is approximately the voltageoutput of each of the racks and is 33% higher than the output voltage ofthe battery pack of FIG. 7 a. The ampere-hour capacity of this batterypack configuration is the sum of the ampere-hour capacity of the two newrack groupings in parallel. The battery pack configuration of FIG. 7 bcan provide 50% more voltage and therefore 50% more power than thebattery pack configuration of FIG. 7 a. However, the battery packconfiguration of FIG. 7 b has 50% less ampere-hour capacity than thebattery pack configuration of FIG. 7 a. Switching from the configurationof FIG. 7 a to the configuration of FIG. 7 b has the advantage ofproviding a power boost such as may be required, for example, in anemergency or starting up a hill. The voltage of the battery pack is thevoltage of 2 rack groupings and the capacity rating of the battery packis the capacity rating of 3 times the rating of individual batteryunits.

When an additional surge of power is required, one rack module can beswitched automatically or manually from parallel to having half itsracks in series with each of the other two rack modules as shown in FIG.7 a and 7 b. The switching can be done under manual or automatic controland heavy duty, high current switches known to those in the art, suchas, for example, a solenoid- or relay-operated contact switch orswitches which can be operated manually or by logic control. Themeasured parameter for switching from series mode to parallel mode andfrom parallel mode to series mode can be the power output from thebattery pack. When the measured power output is lower than a selectedthreshold, the mode is switched from parallel to series and, when thepower output is less than the selected threshold, the mode is switchedfrom series to parallel.

The strategy of switching racks of energy storage units from parallel toseries configurations, as described above, can also be readily carriedout when the energy storage unit is a bank of energy storage capacitors.

This invention most preferably utilizes individual chopper circuits tocontrol direct current to each DC traction motors. DC motors haveperformed as the motive force in a variety of applications includinglocomotives where, typically, multiple direct current motors are used.For example, locomotives may employ 2 to 8 driving axles, each drivingaxle having one DC traction motor.

It is known in the art to control the speed of a direct current seriesmotor by using a chopper circuit which includes a main switch device inseries with the motor and a bypass current path. This is a moreefficient form of power control for locomotives than using resistancecontrol systems. With a chopper circuit, the control of the speed of thetraction motor is achieved by varying the power pulses supplied to themotor so that average power supplied is what is required and power isnot wasted by dissipation in resistance control systems. A thyristor isone type of main switch device used in early chopper circuits. It hassince been replaced by the more versatile Insulated Gate BipolarTransistors (“IGBTs”).

The main elements of a typical chopper circuit, as used in the presentinvention, are shown in FIG. 8. The chopper circuit has input terminals8001 through which current flows into the circuit. The main current flowis along path 8004 which passes through an IGBT switch 8003 and atraction motor 8002. The main current path 8004 is active when the inputpower source (not shown) is powering the traction motor 8002. When theIGBT 8003 is switched to its off position, current is forced to flowthrough the free-wheeling path 8006 by the free-wheeling gate 8005,which is shown as being a diode. The chopper circuit thus controls thespeed of the motor by switching the input voltage on and off dependingon what average output power is required; the longer the chopper isswitched on, the higher the average output power. The time intervalduring which the chopper is switched on is known as the on-time; theinterval during which the chopper is switched off is known as theoff-time. The ratio of the on-time of the power pulse to the off-time ofthe power pulse is often referred to as the-mark-to-space ratio orchopper ratio. The elements comprising a typical chopper circuit arediscussed above as part of the detailed description of FIG. 1.

In the present invention, there is preferably a chopper circuit,including its free-wheeling gate, associated with each traction motor.In other words, each motor typically has, in addition to a correspondingmain current path and main drive (or chopper) switch, a correspondingfree-wheeling path and free-wheeling gate. This is illustrated in FIG. 9which shows four traction motors, each having an individual choppercircuit. The main drive switches are shown here as Insulated GateBipolar Transistors (“IGBTs”) that are switching devices that do notrequire commutating and are capable of sequentially pulsing the powersource to the different motors at a very fast rate. FIG. 9 shows anexample of an electrical schematic for a battery energy storage systemproviding power for four DC traction motors. The battery pack 9001 isshown in two sections separated by an emergency manual disconnect 9002.The battery pack is connected to the traction motor system 9005 bydisconnect switches 9003 which are controlled by the locomotive computersystem. A large bank of surge capacitors 9004 are connected across thebattery pack. The battery pack voltage is monitored by voltage sensor9021 and the battery pack output current is measured by current sensor9022. The current sensor 9022 is used in the determination of the stateof charge of the battery pack as discussed above with reference to FIG.1 which discusses this method of setting the upper and lower set pointsthat define the operational range of the energy storage unit.

The four traction motor systems 9005 are shown here connected inparallel with the battery pack 9001. Four DC traction motors 9006 areshown, each associated with its own individual chopper circuit 9007.Each of the traction motors 9006 are comprised of a field coil 9011which is connected to a reverser switch 9012 and an armature 9021; amain circuit path 9009 controlled by an IGBT 9020; a free wheelingcircuit path 9008 and free-wheeling gate 9010. The IGBT 9020 iscontrolled by the locomotive computer system. Each chopper circuit 9007is protected by a fuse 9013 and a scrubber filter capacitor 9014.Together, the fuse 9013 and filter 9014 act to control the voltagetransients as the chopper circuit 9007 switches from pulse or drivenmode to free-wheeling mode or visa versa, thus reducing the risk ofoverheating and extending the lifetime of the IGBT 9020. The filter 9014also acts to smooth any rapid current fluctuations through the tractionmotors 9005 as the chopper circuit 9007 switches from pulse or drivenmode to free-wheeling mode or visa versa. The main current through eachtraction motor 9006 is monitored by a current transducer 9015.

As will be appreciated, in the driven mode, the chopper switch isactivated such that the at least most of the current passes along themain current path and through the traction motor while in the freewheeling mode the chopper switch is deactivated such that at least mostof the current passes along the free-wheeling or bypass path and throughthe traction motor. FIG. 9 also shows a configuration to effect theswitching necessary to reverse the motor direction by reversing thecurrent flow through the field coils.

In prior applications, a single chopper circuit has been used to controlthe speed of all of the DC traction motors. This has a number ofdisadvantages. For example, if one of the wheels is slipping(non-synchronous wheel slip), the chopper reduces power to all of themotors which risks further exacerbation of the problem.

Typically, pulses are applied to different motors during discrete(nonoverlapping) time periods. In other words, during a selected firsttime period (which is a subset of a time interval) a first electricalpulse is applied to a first traction motor but not to a second(different) traction motor, and, during a selected second time period, asecond electrical pulse is applied to a second traction motor and not tothe first traction motor. Thus, during the selected first time periodthe first traction motor is in the driven mode while the second tractionmotor is in the free-wheeling mode and during the selected second timeperiod the first traction motor is in the free-wheeling mode while thesecond traction motor is in the driven mode.

The advantages of individual chopper circuits with each traction motorare illustrated in FIGS. 10 through 14 which show an example ofsequencing power pulses to four individual motors and the resultant netdraw on the energy storage battery, for a number of cases.

FIGS. 10 a, b, c, d and e show a time sequence of short pulses 10001 toeach motor typical of locomotive start up at a low throttle condition.The pulses 10001 in each sequence are shown along a time axis 10002which is a common time axis for each sequence. Since the voltageamplitude of the pulses 10001 is approximately constant for a largeenergy storage battery pack, the pulse amplitudes 10003 may beconsidered current or power pulses. Each motor receives a power pulse10001 at a different time. FIG. 10 a represents the pulses provided to afirst traction motor; FIG. 10 b to a second traction motor; FIG. 10 c toa third traction motor; and FIG. 10 d to a fourth traction motor. FIG.10 e shows the sum of the individual motor sequences 10004 which is alsothe net power draw from the battery pack. In this case, the batterydischarge is intermittent and the battery current draw is equal to thecurrent through each individual motor. In the prior art where all motorsare pulsed at the same time, the battery current draw is equal to thesum of the currents through each individual motor. Since batteryinternal heating is proportional to I²R where I is the battery currentand R is the battery internal resistance, an advantage of the presentinvention is to minimize battery heating by time spacing the powerpulses to each motor. Also, each motor receives a power pulse which isthe same amplitude as the output power of the battery pack. As anexample, each traction motor has peak power pulses of 1,120 kW and anaverage power of 140 kW (pulse width is ⅛ of the time between pulses).The battery pack likewise would have peak power pulses of 1,120 kW andan average power output of 560 kW (four motors averaging 140 kW).

FIGS. 11 a, b, c, d and e show a time sequence of pulses to each motorwhere the pulses 11001 are spaced 11002 such that there is zero timebetween any two pulses form the four sequences. FIG. 11 a represents thepulses provided to a first traction motor; FIG. 11 b to a secondtraction motor; FIG. 11 c to a third traction motor; and FIG. 11 d to afourth traction motor. FIG. 11 e shows the sum 11003 of the individualmotor sequences which is again is the net power draw from the batterypack. For a four motor locomotive such as shown in FIG. 9, thiscorresponds to pulse widths that are 25% of the time between pulses inan individual sequence. In this case, the battery is operatingcontinuously as shown by its power output 11003. Also for this case,each motor receives a power pulse which is the same amplitude 11004 asthe output power 11005 of the battery pack. Assuming the same batterypack and traction motors as used in FIG. 10, in the example of FIG. 11,each traction motor has peak power pulses of 1,120 kW and an averagepower of 280 kW (pulse width is ¼ of the time between pulses). Thebattery pack now has peak power pulses of 1,120 kW which is the same asits average power output of 1,120 kW.

In the cases illustrated by FIGS. 10 and 11, only one of the tractionmotors is in driven mode while the others are all in free-wheeling mode.

FIGS. 12 a, b, c, d and e show a time sequence of power pulses 12001that have some overlap in time as might be the case for higherlocomotive speed or throttle power setting. FIG. 12 a represents thepulses provided to a first traction motor; FIG. 12 b to a secondtraction motor; FIG. 12 c to a third traction motor; and FIG. 12 d to afourth traction motor. FIG. 12 e shows the sum of the individual motorsequences 12003 which is again is the net power draw from the batterypack. In this case, the battery is operating continuously. Each motorreceives a power pulse 12001 which has a constant amplitude 12002. Thepower draw 12003 on the battery pack is variable, reflecting the overlapin individual motor power pulses. In actual practice, the batteryfiltering capacitor tends to smooth out the power pulse from that shown.Assuming the same battery pack and traction motors as used in FIG. 10,in the example of FIG. 12, each traction motor has peak power pulses of840 kW and an average power of 315 kW (pulse width is ⅜ of the timebetween pulses). The battery pack now would have peak power pulses of1,680 kW and an average power output of 1,260 kW.

FIGS. 13 a, b, c, d and e show a time sequence of power pulses 13001that have substantial overlap in time. In this case, the battery isoperating continuously. FIG. 13 a represents the pulses provided to afirst traction motor; FIG. 13 b to a second traction motor; FIG. 13 c toa third traction motor; and FIG. 13 d to a fourth traction motor. FIG.13 e shows the sum 13003 of the individual motor sequences which isagain is the net power draw from the battery pack. Each motor receives apower pulse 13001 which has a constant amplitude 1300. The power draw13003 on the battery pack is has increased and remains variable,reflecting even greater overlap in individual motor power pulses. Inactual practice, the battery filtering capacitor tends to smooth out thepower pulse from that shown. Assuming the same battery pack and tractionmotors as used in FIG. 10, in the example of FIG. 13, each tractionmotor has peak power pulses of 630 kW and an average power of 394 kW(pulse width is ⅝ of the time between pulses). The battery pack nowwould have peak power pulses of 1,890 kW and an average power output of1,575 kW.

FIGS. 14 a, b, c, d and e show a time sequence of power pulses 14001that are continuous and the battery is also operating continuously. FIG.14 a represents adjoining pulses provided to a first traction motor;FIG. 14 b to a second traction motor; FIG. 14 c to a third tractionmotor; and FIG. 14 d to a fourth traction motor. FIG. 14 e shows the sum14003 of the individual motor sequences which is again is the net powerdraw from the battery pack. In this final case, the battery is operatingcontinuously and each motor receives a power pulse 14002 which isapproximately one quarter the amplitude of the output power 14003 of thebattery pack. Assuming the same battery pack and traction motors as usedin FIG. 10, in the example of FIG. 14, each traction motor hascontinuous power of 560 kW and the battery pack has a continuous powerdraw of 2,240 kW which is four times that of each motor.

In most locomotive operations, the engineer applies power by selecting athrottle setting (usually a notch setting from 1 to 8). The throttlesetting causes the logic controller to apply the required power to thetraction motors using a preset logic. In some cases, the engineer maywant to set a particular locomotive speed, usually a low speed such as,for example, might be required by a switching locomotive. A particularspeed setting may be accomplished by the engineer using a rheostat tocontrol power to the traction motors, rather than by selecting one ofthe throttle notch settings. A more preferred method is for the engineerto set the desired speed by the use of a touch screen or other type ofcomputer input. In the latter case, the speed setting may beaccomplished by the logic controller which would prescribe a presetpower pulse width setting for the chopper circuits. The power pulsewidths would be set, typically to a very short pulse widths, to providea low average power to the traction motors that is known to result inthe desired locomotive speed. More preferably, the logic controllerwould utilize the tachometers on the drive axles to control the speed ofthe locomotive to the desired value. This latter approach would resultin the desired locomotive speed being more accurately achieved.

If an energy storage capacitor bank is used in place of a battery pack,then the output of the capacitor bank may require additionalconditioning to match the voltage-current requirements of DC tractionmotors. This is because a battery pack provides an approximatelyconstant voltage output over most of its discharge range, whereas acapacitor bank discharges as a decaying voltage waveform. The additionalconditioning may be accomplished with yet another chopper circuit, suchas for example a buck-boost chopper circuit, or any of a number ofwell-known pulse forming networks utilized in the high energy capacitorbank industry. FIG. 15 shows a general electrical schematic of acapacitor based propulsion circuit which includes the positioning ofadditional power conditioning and pulse shaping elements. The capacitorbank 15001 is shown in two sections and is connected to a powerconditioning/pulse shaping unit 15002 which includes inductors and otherreactive elements, as will be known to one of ordinary skill in the art,to maintain the output power pulses of the capacitor bank 15001 at leastsubstantially constant in amplitude. In other words, the waveformrepresenting the amplitude of the output as a function of time is atleast substantially linear. The output of the power conditioning section15002 drives a series of four traction motors 15003 which may beconfigured identically to those shown in FIG. 9.

A truck assembly in the railroad industry is a frame to which one ormore axle and wheel assemblies are mounted. The truck assembly alsoincludes suspension and brake system elements. In addition, there areprovisions for mounting AC or DC traction motors. The present inventiongenerally utilizes truck assemblies with only DC traction motors.

The primary specifications for DC traction motors used in the presentinvention are typically:

-   -   (a) a power in the range of about 300 to 1,200 horsepower;    -   (b) a tractive force in the range of up to about 25,000 lbs;    -   (c) a maximum voltage rating of about 1,300 volts; and    -   (d) a maximum current rating of about 1,800 amperes for short        periods, typically less than 3 minutes, depending on the level        of air cooling available.

The braking system on a locomotive is typically an air brake system inwhich the charging generator or energy storage unit are utilized tooperate an auxiliary compressor to pressurize an air reservoir. The airreservoir provides air pressure to the brake cylinders such as shown inFIGS. 16 and 17. FIGS. 16 a and b shows a top view FIG. 16 a and sideview FIG. 16 b of a 3 axle truck assembly 16001 with a tread brakeconfiguration. When activated, air brake cylinders 16003 engage brakeshoes 16004 against the wheel treads 16005. The air brake cylinders16003 are pressurized by compressed air by a system of air brake lines16006.

FIG. 17 shows an isometric schematic of a typical rail air-brake system.Compressed air is maintained in the main air reservoirs 17001 which arereplenished by the main air-compressor 17005 through air-line 17002. Asystem of control valves 17006 direct compressed air via air-brake lines17007 to the various brake cylinders 17008 which in turn operate thebrake shoes 17004. In a long train, the air pressure at variouslocations in the system will not be exactly equal during application orrelease of the brakes because of the time required for air to flow longdistances through the air lines.

As a result of the time delay for air-pressure to be released after thecommand for brake release is given by the engineer, one or more of theair brakes on a locomotive wheel can become locked, causing flat spotsto be developed on the affected wheel treads. If these flat spots aresevere, the wheels must be removed, and turned down by machining orreplaced. It is therefore a part of the present invention to include theoption of an air-actuated brake release system that can rapidly unlockthe brakes on a wheel.

In the present invention, the brake shoes are designed as shown in FIG.18 so that air pressure may be applied to the brake shoe to force it tounlock. FIG. 18 shows a schematic view of a possible brake releaseconfiguration. Compressed air is fed via an air line 18002 a plenum18001. The plenum 18001 is formed inside the brake shoe housing 18003and on the rear side of the brake show 18004. When activated, the brakerelease system operates by forcing high pressure air through holes 18006installed in and passing through the brake shoe 18004. This highpressure air is forced between the brake shoe friction surface 18007 andthe braking surface of the wheel 18008, as indicated by arrows 18005, toeffect immediate release of the brake shoe 18004 from the wheel 18008.The diameter and location of the holes 18006 are designed so that theair pressure applied between the brake shoe 18004 and the wheel brakingsurface 18008 exerts a substantially greater force to disengage thebrake shoe 18004 than the force exerted by the air-brake cylinder 18009which is engaging the brake shoe 18004. The release force is preferablybetween about 10% and 30% greater than the applied braking force. Thepressurized air in the brake release plenum 18001 is applied on commandby control valves 18010 which may be positioned as shown in FIG. 18. Thepressure in the air-actuated brake release system may be the same orhigher than the air pressure in the brake system. Developing a higherpressure locally can be accomplished by any number of well-known meanssuch as, for example, a cylinder with a variable area piston. The aboveair-brake release system may be installed using either a tread brake ordisc brake configuration.

FIG. 19 shows an air release plenum 19001 installed in a typical treadbrake shoe 19002. The air-brake mechanism 19003 operates in the normalmanner to engage the shoe 19002 with the tread of the wheel 19004 toeffect braking. The air-brake release system is shown operating off apressurized air-line 19005 which may be connected to the air brakesystem directly or by a variable area piston (not shown).

FIG. 20 shows an air release plenum 20001 installed in typical discbrake pads 20002. The air-brake mechanism 20003 operates in the normalmanner to engage the pads 20002 with the sides of the wheels 20004 toeffect braking. The air-brake release system is shown operating off apressurized air-line 20005 which may be connected to the air brakesystem directly or by a variable area piston (not shown).

Although not incorporated in the current embodiment, regenerativebraking can be incorporated into the locomotive system, especially forlocomotives operating at speeds greater than approximately 50 km/hr. Ifincorporated, regenerative braking systems would be installed usingindividual circuits associated with each axle such as is being done byapplying individual chopper circuits to each axle in the currentpreferred embodiment.

When each drive axle on the locomotive has its own chopper circuit, thepower to the axle whose wheels are detected to be non-synchronouslyslipping, can be reduced in until the slipping is eliminated. Thisindividual power control to each drive axle is a primary feature of thepresent invention. As will be discussed in more detail below, thetraction motor electrical current and temperature and the axlerotational speed and temperature can be individually monitored andcontrolled by a computer monitoring system.

The logic controller is divided into three elements. These are:

-   -   (a) control of the power to the traction motors;    -   (b) control of the charging unit that charges the main energy        storage apparatus; and    -   (c) control of the wheel braking function.

The main power control logic is discussed below with reference to flowdiagram of FIG. 21.

-   -   1. To begin the cycle, the engineer gives total tractive power        command 21001 (specifies total power requested)    -   2. Measure battery volts or the state of charge of the battery        or both 21002 to determine if charging generator needs to be on        or off        -   a. when the charging generator is on 21003            -   i. indicate a warning 21031 when the battery voltage or                state of charge or both are below the lower set point                and leave the charger on 21004            -   ii. take no action when the battery voltage or state of                charge or both are in the normal range between the upper                and lower set points 21005            -   iii. shut the charging generator off when the battery                voltage or state of charge or both are above upper set                point 21006        -   b. when the charging generator is off 21007            -   i. turn on the generator when the battery voltage or                state of charge or both are below upper set point 21008.            -   ii. leave the generator off when the battery voltage or                state of charge or both are above the upper set point                21009    -   3. Apply required amount of power to all DC traction motors by        phasing power output to each DC traction motor according to        predetermined algorithm 21010    -   4. Measure average battery output volts and current to determine        battery output power and state of charge 21011. When the battery        output power or state of charge is below its lower set point,        indicate a warning on the warning screen 21012. Otherwise        indicate the operational battery condition on the battery        monitor and battery status screens 21013.    -   5. Loop through all axles with DC traction motors. Do this        preferably simultaneously or less preferably in sequence. For        each DC traction motor (such as 21014 for example):        -   a. sense rotational speed (locked, normal or slip) 21015            -   i. when the brakes are not applied and any wheels are                locked 21016, apply air release to the locked wheels                21017                -   (1) take no further action when brake release is                    confirmed                -   (2) when brake release is not confirmed, reapply air                    release and indicate a warning            -   ii. take no action when no wheel slippage and no wheels                locked 21019            -   iii. when a wheel is indicated to be slipping 21020,                reduce the power to the axle by a specified amount 21021                -   (1) if the wheel continues to slip, reduce power                    again, and continue to do so in prescribe increments                    until slipping stops 21022                -   (2) take no action when slipping is not occurring        -   b. measure axle traction motor current 21023        -   c. adjust power as required by modifying power algorithm            21024    -   6. To end the cycle, optionally measure all motor, wheel and        brake temperatures and adjust algorithms 21025. As will be        appreciated, the various set points for controlling the prime        energy source, the conversion apparatus, the energy storage        units, the chopper circuits and the brake release systems may be        somewhat temperature sensitive and this sensitivity can be        accounted for by algorithms that reflect known change in set        points as a function of temperature.

The charging unit control logic is discussed below in further detailwith reference to flow diagram of FIG. 22 a and 22 b. This logic applieswhen the charging generator is on. There are at least two methods forcontrolling the charging power so that the alternator presents aconstant load to the prime energy source.

One method is to control the charging unit by monitoring engine rotaryspeed (RPMs). With reference to FIG. 22 a:

-   -   1. Begin the cycle by monitoring the engine (prime energy        source) revolutions per minute (RPMs) 22001        -   a. take no action when the RPMs are within the range set for            maximum fuel efficiency 22002        -   b. when the RPMs are below the lower set point for RPMs,            reduce the excitation current to the alternator until the            RPMs increase to within their set range for maximum fuel            efficiency 22003        -   c. when the RPMs are above the upper point of RPMs, increase            the excitation current to the alternator until the RPMs            decrease to within their set range for maximum fuel            efficiency 22004    -   2. End the cycle by repeating the monitoring process

The second method is to control the charging unit by monitoring DCcharging power. With reference to FIG. 22 b:

-   -   1. Begin the cycle by monitoring the engine (prime energy        source) revolutions per minute (RPMs) 22011    -   2. Monitor the DC output volts and current of the charging        system 22012. This determines output charging power        (volts×amperes=watts).        -   a. take no action when the output power is within the range            set for maximum fuel efficiency 22013        -   b. when the output power is below the lower set point of            output power, increase the excitation current to the            alternator until the output power increases to within its            set range for constant load presented to the prime energy            source so that the fuel efficiency can be maintained at or            close to its maximum 22014        -   c. when the output power is above the upper set point of            output power, reduce the excitation current to the            alternator until the output power decreases to within its            set range for constant load presented to the prime energy            source 22015    -   3. Monitor the engine rpms to ensure that they are within the        set operating range 22016        -   a. when the RPMs are within the range set for maximum fuel            efficiency, take no action 22017        -   b. when the RPMs are below the lower set range of RPMs,            reduce the excitation current to the alternator until the            RPMs increase to within their set range for maximum fuel            efficiency 22018        -   c. when the RPMs are above the upper set range of RPMs,            increase the excitation current to the alternator until the            RPMs decrease to within their set range for maximum fuel            efficiency 22019    -   4. End the cycle by repeating the monitoring process (steps        22011, et seq.)

Yet another method for monitoring engine RPMs is to measure the powerfrequency of the generator conversion apparatus. The logic flow usingthis method is identical to that of FIG. 22 b with “generator poweroutput” replaced by “generator power frequency”.

The control logic for the braking system is discussed below in furtherdetail with reference to flow diagram of FIG. 23 a and 23 b. FIG. 23 aapplies when the brakes are applied or activated while FIG. 23 b applieswhen the brakes are released or deactivated.

With reference to FIG. 23 a for brakes on:

-   -   1. To begin the cycle, the engineer gives the command to apply        the brakes 23001:    -   2. The true ground speed of the locomotive is determined 23090        by a doppler radar system or other independent motion detector        in the locomotive. This is necessary if there is synchronous        wheel slip or synchronous wheel locking. In either case, the        axle rotary speed sensors would not correctly indicate        locomotive ground speed:    -   3. Loop through all axles with air brake systems. Do this        preferably simultaneously or less preferably in sequence. For        each axle (such as 23002 for example):        -   a. sense rotational speed (locked, normal braking, no            braking) 23003            -   i. when the brakes are on and the wheels are indicated                to be locked, apply air release 23004                -   (1) when wheel release is confirmed, take no further                    action 23005                -   (2) when wheel release is not confirmed, reapply air                    release and indicate a warning 23006            -   ii. when braking is indicated to be normal, take no                further action 23007            -   iii when no braking is sensed, indicate a warning 23020    -   4. End the cycle by optionally measuring all temperatures 23008.        With reference to FIG. 23 b for brakes off:    -   1. To begin the cycle, the engineer gives the command to release        the brakes 23011:    -   2. The true ground speed of the locomotive is determined 23091        by a doppler radar system or other independent motion detector        in the locomotive:    -   3. Loop through all axles with air brake systems. Do this        preferably simultaneously or less preferably in sequence. For        each axle (such as 23012 for example):        -   a. sense axle rotational speed (locked, normal braking,            brakes released) 23013            -   i. apply air release when brakes are on or the wheels                are locked 23014                -   (1) continue when wheel release is confirmed 23015                -   (2) when release is not confirmed, reapply air                    release and indicate a warning 23016            -   ii. take no further action when braking is indicated to                be off 23017    -   4. To end the cycle, optionally measure brake temperatures 23018

In operation, the PLC determines the power requirement for each motor ateach time interval based on inputs from the input device, ramping,derate evaluation logic and detection scaling. Based on such inputs thePLC calculates the necessary pulse width for each motor. The selectedpulse widths are then provided to the switch drives which sequentiallyprovide the desired pulse widths of power to the DC motors. When thelocomotive is starting for example, a high voltage difference existsbetween the battery and the motor so a high current can be applied tothe motor, which only requires a short pulse duration to meet the powerrequirement specified. This makes available the full supply voltage forstarting in either direction. As the motor speed increases, a backvoltage is created which reduces the effective voltage or voltagedifference between tho battery and the motor, thus necessitating alonger pulse to achieve the same power. If wheel slippage is detected,power can be shut off or reduced appropriately to the relevant motor.

As will be appreciated, the control system for the various components ofthe locomotive requires a Graphical User Interface display (“GUI”) toprovide a user interface for viewing the various monitored parametersand the operational states of the various components and providingoperational commands to the various components. This GUI is preferablyimplemented using a series of related display screens which areconfigured to receive touch screen commands. This system of screensallows the operator and maintenance crew to monitor and control, forexample, the state of the charging generator, the battery pack, theindividual drive axles and other functions.

The flow chart shown in FIG. 24 shows an example of a touch screensystem. Not shown are examples of an air brake system monitor screen andindividual axle brake status screens which can be included in the screensystem of the present invention. The individual screens shown in flowchart of FIG. 24 are a Main Menu Screen 24001 which controls a number ofsecondary screens. The secondary (or child) screens include: a BatteryMonitor Screen 24002; a Battery Status Screen 24003; a Traction MotorSummary Screen 24004; a Warnings Screen 24005; a Control Tools Screen24006; and a Derate and Shutdown Screen 24007. The Traction MotorSummary Screen 24004 controls individual Traction Motor Screens 24011,the number of Traction Motor Screens 24011 being equal to the number ofdrive axles on the locomotive. The individual Traction Motor Screens24011 are therefore grandchildren of the Main Menu Screen 24001 andchildren of the Traction Motor Summary Screen 24004. The Control ToolsScreen 24006 controls three informational screens which include: anAlarm History Screen 24021; a Digital Input Monitor Screen 24022; and anOutput Monitor Screen 24023. The informational screens 24021, 24022 and24023 are therefore grandchildren of the Main Menu Screen 24001 andchildren of the Control Tools Screen 24006.

As shown in FIG. 25, the Main Menu Screen accesses the followingsecondary screens:

-   -   (a) the Traction Motor Summary Screen 25001 (shown in FIG. 26);    -   (b) the individual Traction Motor Screens 25002 (shown in FIG.        27);    -   (c) the Battery Monitor Screen 25003 (shown in FIG. 29);    -   (d) the Battery Status Screen 25004 (shown in FIG. 28);    -   (e) the Control Tools Screen 25005 (shown in FIG. 30);    -   (f) the Warnings Screen 25006 (shown in FIG. 34); and    -   (g) the Derate and Shutdown Screen 25007 (shown in FIG. 35).

In addition, several functions are monitored and controlled from theMain Menu Screen. The functions monitored include:

-   -   (a) the locomotive status 25010, which reports on the state of        the locomotive, including for example: throttle positions;        battery and other electrical conditions; forward, neutral or        reverse status; wheel slip;    -   (b) the charger status 25011, which reports on the state of the        charger including for example: charger electrical conditions;        temperatures; and status such as running or shutting down;    -   (c) the locomotive speed 25012, which displays the speed in        miles per hour (mph) or other units such, as for example,        kilometers per hour (kph);    -   (d) the throttle notch position 25013, which displays the        throttle notch position (from 1 to 8) set manually by the        locomotive engineer;    -   (e) the battery pack voltage 25014, which displays the voltage        at the output terminals of the battery pack;    -   (f) a traction motor status field 25015, with a change in field        color indicating that there is a change in status of one or more        of the DC traction motors;    -   (g) a warning field 25016, with change in field color indicating        that there is a change in status of one or more of the system        warnings; and    -   (h) a derate or shutdown field 25017, with a change in field        color indicating that there is a change in status of derate        (going to or remaining in idle) or shutdown (emergency        locomotive shutdown).

The functions controlled include a charger manual control 25018, withthis button being used to manually start and stop the battery charginggenerator.

A child screen off of the Main Menu Screen is the Traction Motor SummaryScreen depicted in FIG. 26 which accesses the individual Traction MotorScreens 26001. The Traction Motor Summary Screen shows, for eachtraction motor 26002, the position of the various contactors 26003, thecurrent going through each traction motor 26004, the reverser status26005, the ground fault conditions 26006 and the wheel slip indicator21007.

The Traction Motor Summary Screen also allows the operator to read andselect instantaneous or average current reading 26008 from any of thetraction motors. The Traction Motor Summary Screen allows the operatorto go back to the Main Menu Screen 26009 or to the Warnings Screen 26010or to any of the Traction Motor Screens 26002.

A typical Traction Motor Screen, shown in FIG. 27, provides more detailabout the status of each traction motor including contactor status27001, motor status 27002, reverser status 27003, wheel slip status27004 and motor current 27005. This screen also allows the operator toopen contactors 27011, monitor the motor cutout status 27012, cut outthe traction motor 27013 and de-energize the reverser 27014. Field 27021of each of the Traction Motor Screens allows the operator to go back tothe main menu screen.

The Battery Status Screen, shown in FIG. 28, displays details about theelectrical state of the energy storage unit (e.g., battery) and thestatus of the mechanical-to-electrical conversion device (e.g., charginggenerator ). The displayed fields include:

-   -   (a) B-Contactor Status 28001, which reports whether the Battery        contactors are open or closed;    -   (b) Battery Power 28002, which displays the current power being        delivered by the energy storage unit to the drive system;    -   (c) Battery voltage 28030    -   (d) Battery current 28031    -   (e) Battery Energy Delivered to Date 28003, which provides the        total amount of kWh the energy storage unit has delivered to the        drive system;    -   (f) Battery State of Charge 28004, which depicts, in a bar graph        format, the state of charge of the energy storage unit by        measuring the amp-hours in and the amp-hours out;    -   (g) Charger Status 28005, which reports what the        mechanical-to-electrical conversion device (e.g., charging        generator ) is currently doing such as, for example, mode of        operation (warming up etc); current charge, load charge, cooling        status;    -   (h) Charger Power 28006, which reports the power being produced        by the mechanical-to-electrical conversion device (e.g.,        charging generator) for charging the energy storage unit. When        the conversion apparatus is not running, this field will provide        a negative value to reflect the power draw out of the storage        unit by the auxiliary systems; and    -   (i) Charger Energy Produced to Date 28006, which reports the        power that the conversion device has produced for replacing the        energy drawn from the energy storage unit by the drive system        but does not include the draw of the auxiliaries.    -   (j) Charger frequency 28032    -   (k) Charger current 28033

In addition, the Battery Status Screen allows control of themechanical-to-electrical conversion device (e.g., charging generator)through:

-   -   (a) the Charger Manual Control Button 28011, which can be used        to manually start and stop the conversion device; and    -   (b) the Charger Disabler Button 28012, which allows the operator        to disable the charge scheme for the conversion device,        preventing it from starting automatically or through the manual        charger control button 28011.

The Battery Status Screen is a child of the Main Menu Screen, isaccessed from the the Main Menu Screen and, using field 28013, allowsthe operator to return to the Main Menu Screen.

The Battery Monitor Screen, shown in FIG. 29, relays the signals fromthe battery monitoring system to the operator. The three squares 29001on the left correspond to the three left-most LEDs in the batterymonitoring system box, which correspond to temperature faults in theenergy storage unit. The field 29003 directly below the three squares29001 provide more detail about the fault detected. The two squares29004 on the right correspond to the right most LEDs in the batterymonitoring system box, which correspond to voltage faults. The field29006 below the two squares 29004 give more detail about the faultcondition detected. This screen is a child of the Main Menu Screen, isaccessed from the Main Menu Screen and, using field 29008, allows theoperator to return to the Main Menu Screen.

The Control Tools Screen, shown in FIG. 30, is a child of the Main MenuScreen and, in turn, accesses the various informational screens, such asthe Alarm History Screen of FIG. 31, the Digital Input Monitor Screen ofFIG. 32 and the Output Monitor Screen of FIG. 33.

The Control Tools Screen shows the following fields:

-   -   (a) a 600 V ground fault indicator 30001;    -   (b) ground leakages 30002 detected on each traction motor;    -   (c) battery power set point 30003;    -   (d) battery current 30004;    -   (e) horsepower being developed 30005; and    -   (f) traction motor leakage detected during last test 30006.

The Control Tools Screen also has a ground fault detection controlbutton 30011, which turns color when a ground fault has been detected.Pushing the ground fault detection control button 30011 starts a groundfault detection process. This screen is a child of the Main Menu Screen,is accessed from the Main Menu Screen and, using field 30012, allows theoperator to return to the Main Menu Screen. This screen allows theoperator to access the Alarm History Screen via field 30013, the DigitalInput Monitor Screen via field 30014 and the Output Monitor Screen viafield 30015.

The Alarms History Screen, shown in FIG. 31, keeps a record of all ofthe alarms and warnings 31001 reported on the touch-screen. The AlarmHistory Screen is a child of the Control Tools Screen and allows theoperator to go back to the Main Menu Screen via field 31002, to theWarnings Screen via field 31012 or to the Derate and Shutdown Screen viafield 31013. The Alarm History Screen also has a button 31014 thatallows the operator to clear the list 31001 of past alarms and warnings.

A Digital Input Monitor Screen, shown in FIG. 32, indicates the variousinputs to the control computer monitors and shows the status of thatinput. If there is no signal seen by the control computer, the square32001 will be black, and if a signal is present, square 31001 will begreen. The various input boards are given an address 32002, such, as forexample, “I” means input board. The first number 32003 designates whichboard (3, 4, or 5), and the second number 32004 designates which tab onthe board (0 to 15). This screen also has a button 3201 l to reset thepulse width board signal. The Digital Input Monitor Screen allows theoperator to go back to the Main Menu Screen via field 32012, the ControlTools Screen via field 32013, or to the Output Monitor Screen via field32014.

An Output Monitor Screen, shown in FIG. 33, shows the various output thecontrol computer uses, and the status of the outputs. If there is nosignal, the square 33001 will be blue, if there is a signal going out,then the square 33001 is red. The Output Monitor Screen also has anoutput control button 33011, which allows the operator to override thelogic of the control computer and to enable any of the outputs manually.The Output Monitor Screen is a child of the Control Tools Screen andallows the operator to go back to the Control Tools Screen via field33012 or to the Digital Input Monitor Screen via field 33013.

A Warnings Screen, shown in FIG. 34, displays minor alarms that havebeen detected.

The warnings contains information on:

-   -   (a) an improper reverser condition or mismatch field 34001;    -   (b) a throttle mismatch field 34002;    -   (c) a B-contactor mismatches field 34003 and P-contactor        mismatches field 34004;    -   (d) a high or low current warnings field 34005 indicating an        unacceptably high or low current on any of the traction motors        34006;    -   (e) a low voltage warning field 34007 indicating a low voltage        on the energy storage unit;    -   (f) a ground leakage field 34008; and    -   (g) a high temperature warning field 34009 indicating an        unacceptably high temperature on the any of the traction motors,        in the energy storage unit, or on the chopper board heat sinks.

The Warnings Screen is a child of the Main Menu Screen and allows theoperator to go back to the Main Menu Screen via field 34011, the BatteryWarning Screen via field 34012 or the Derate and Shutdown Screen viafield 34013.

A Derate and Shutdown Screen, shown in FIG. 35, displays alarms thatcaused the locomotive to unload and/or prevent it from loading to fullpower. Some functions flagged on this screen may be controlled manuallyand some are controlled automatically. An example of the latter is anautomatic reduction in power to a motor whose IGBT has exceeded itspreset temperature limit. This screen includes information on:

-   -   (a) an off/shutdown alarms field 35001 indicating an alarm that        caused the locomotive to do an emergency shutdown where the        B-Contactors opened up;    -   (b) an emergency fuel shutoff indicator button 35002, a stop        command button 35003, a pneumatic control switch button 35004,        an emergency sanding switch button 35005, an isolation switch        condition button 35006, an engine run switch indicator 35007, a        600 VDC ground fault detection button 35008, at least one of the        electrical cabinet doors has been opened indicator 35009,        excessive battery current detected 35010, low battery voltage        indicator 35011, thermal fuse on the filter board short        indicator 35012, and excessive locomotive speed indicator 35013;    -   (c) an idle derate alarm field 35014 indicating an alarm that        have caused the locomotive to go to or remain in idle, but the        B-Contactors have remained closed. This includes conditions        where the generator field switch is off, one or more P-Contactor        has not aligned correctly, or the battery current is being        detected when it should not be;    -   (d) a traction motor high current derate field 35015 indicating        that the locomotive is not developing full power because of high        current in the traction motors;    -   (e) an RVR MM Cut-Out field 35016 indicating that the locomotive        is not developing full power because a reverser will not align        in the given direction, or full power is not being developed        because a traction motor was manually cut out; and    -   (f) a ground derate field 35016 indicating that the locomotive        will not load because there is a 600 V ground fault condition,        or the locomotive will not load because it is in the process of        a ground fault detection test.

The Derate and Shutdown Screen also has a button 35021 that can bepushed to acknowledge an alarm and clear it from the system. The Derateand Shutdown Screen is a child of the Main Menu Screen and allows theoperator to go back to the Main Menu Screen via field 35022.

A number of variations and modifications of the invention can be used.As will be appreciated, it would be possible to provide for somefeatures of the invention without providing others. For example in onealternative embodiment, the various inventive features are applied tovehicles other than locomotives, such as cars, railroad cars, andtrucks. The control logic set forth above may be implemented as a logiccircuit, software, or as a combination of the two.

The present invention, in various embodiments, includes components,methods, processes, systems and/or apparatus substantially as depictedand described herein, including various embodiments, subcombinations,and subsets thereof. Those of skill in the art will understand how tomake and use the present invention after understanding the presentdisclosure. The present invention, in various embodiments, includesproviding devices and processes in the absence of items not depictedand/or described herein or in various embodiments hereof, including inthe absence of such items as may have been used in previous devices orprocesses, for example for improving performance, achieving ease and\orreducing cost of implementation.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of theinvention are grouped together in one or more embodiments for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimed inventionrequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description, with eachclaim standing on its own as a separate preferred embodiment of theinvention.

Moreover though the description of the invention has includeddescription of one or more embodiments and certain variations andmodifications, other variations and modifications are within the scopeof the invention, e.g. as may be within the skill and knowledge of thosein the art, after understanding the present disclosure. It is intendedto obtain rights which include alternative embodiments to the extentpermitted, including alternate, interchangeable and/or equivalentstructures, functions, ranges or steps to those claimed, whether or notsuch alternate, interchangeable and/or equivalent structures, functions,ranges or steps are disclosed herein, and without intending to publiclydedicate any patentable subject matter.

1. A locomotive, comprising: a plurality of direct current tractionmotors corresponding to a plurality of axles and a plurality of driveswitches, each traction motor operating in a driven mode and afree-wheeling mode, wherein in the driven mode a power pulse passesthrough the traction motor and the corresponding drive switch and in thefree-wheeling mode the power pulse passes through the traction motor andbypasses the corresponding drive switch; a plurality of filters, eachfilter corresponding to one of the plurality of direct current tractionmotors, to absorb electrical voltage transients and smooth currentripples through the traction motors resulting from changes between thedriven and free-wheeling modes.
 2. The locomotive of claim 1 furthercomprising: a plurality of free-wheeling bypass circuits, each bypasscircuit bypassing a corresponding one of the plurality of driveswitches.
 3. The locomotive of claim 1, further comprising: a pluralityof chopper circuits corresponding to the plurality of direct currenttraction motors, each chopper circuit comprising the free-wheelingbypass circuit, the drive switch being in electrical communication witha respective direct current traction motor, and at least one of thefilters.
 4. The locomotive of claim 3, wherein, during a selected timeinterval, a first chopper circuit corresponding to a first tractionmotor is in the first mode and a second chopper circuit corresponding toa second traction motor is in the second mode.
 5. A locomotive,comprising: a plurality of electrical storage subunits, wherein in afirst mode the electrical storage subunits are connected electrically inseries and in a second mode the electrical storage subunits areconnected electrically in parallel.
 6. The locomotive of claim 5 furthercomprising: at least one switch to switch the electrical storagesubunits between the first and second modes.
 7. The locomotive of claim5 wherein simultaneously some of the electrical storage subunits areelectrically connected in series and others of the electrical storagesubunits are electrically connected in parallel.
 8. A locomotive,comprising: a plurality of direct current traction motors incommunication with a plurality of axles; a prime energy source; anenergy conversion device, in communication with the prime energy source,to convert the energy output by the prime energy source into directcurrent electricity; and an energy storage device, in communication withthe energy conversion device and the plurality of traction motors, toreceive and store the direct current electricity, wherein the energystorage device comprises a plurality of capacitors operable to store thestored energy.
 9. The locomotive of claim 8 wherein at least most of thestored electricity is stored in the plurality of capacitors.
 10. Thelocomotive of claim 9 further comprising a pulse forming network toconvert the output of the plurality of capacitors to a form acceptableto the traction motors.
 11. A locomotive, comprising: a plurality oftraction motors in communication with a plurality of axles; a primeenergy source for providing power to the plurality of traction motors;and a plurality of air brake systems operatively engaging a respectiveone of the plurality of axles, each air brake system comprising at leastone movable braking surface element and corresponding air-brake cylinderand a fluid-activated brake release, wherein, when a moveable brakingsurface element is locked in position against a braking surface, fluidpressure is applied by the fluid-activated brake release to disengagethe locked moveable braking surface from the braking surface.
 12. Thelocomotive of claim 11, further comprising: an energy conversion device,in communication with the prime energy source, to convert the energyoutput by the prime energy source into direct current electricity; andan energy storage device, in communication with the energy conversiondevice and the plurality of traction motors, to receive and store thedirect current electricity.
 13. The locomotive of claim 11 wherein eachmoveable braking surface element comprises a plurality of holes passingtherethrough and the fluid-activated brake release forces fluid throughthe holes in the moveable braking surface element and against thebraking surface to form a brake release force.
 14. The locomotive ofclaim 13 wherein the force required to unlock a locked braking surfaceelement is the braking force and the release force is at least about 10%greater than the braking force.
 15. A locomotive, comprising: aplurality of direct current traction motors in communication with aplurality of axles; a prime energy source; an energy conversion device,in communication with the prime energy source, to convert the energyoutput by the prime energy source into direct current electricity; anenergy storage device, in communication with the energy conversiondevice and the plurality of traction motors, to receive and store thedirect current electricity; a controller operable to control anexcitation current to the energy conversion device, wherein at least oneof the following statements is true: (i) when a first predetermined setpoint is exceeded by a first monitored parameter, the excitation currentis increased and, when a second predetermined set point exceeds thefirst monitored parameter, the excitation current is decreased andwherein the first monitored parameter is revolutions per minute of amechanical component of the prime energy source and (ii) when the firstpredetermined set point is exceeded by a second monitored parameter, theexcitation current is decreased and, when the second predetermined setpoint exceeds the second monitored parameter, the excitation current isincreased and wherein the second monitored parameter is the output powerof the energy conversion device.
 16. The locomotive of claim 15 whereinthe first and second predetermined set points are selected to produce atleast a desired degree of fuel efficiency for the prime energy source.17. The locomotive of claim 15 wherein (i) is true.
 18. The locomotiveof claim 15 wherein (ii) is true.
 19. A method for providing electricalenergy to an energy storage device in a locomotive, comprising: (a)providing a locomotive comprising: (i) a plurality of direct currenttraction motors in communication with a plurality of axles; (ii) a primeenergy source; (iii) an energy conversion device, in communication withthe prime energy source, to convert the energy output by the primeenergy source into direct current electricity; and (iv) an energystorage device, in communication with the energy conversion device andthe plurality of traction motors, to receive and store the directcurrent electricity; and (b) controlling an excitation current to theenergy conversion device by performing at least one of the followingsteps: (i) when a first predetermined set point is exceeded by a firstmonitored parameter, the excitation current is increased and, when asecond predetermined set point exceeds the first monitored parameter,the excitation current is decreased and wherein the first monitoredparameter is revolutions per minute of a mechanical component of theprime energy source and (ii) when the first predetermined set point isexceeded by a second monitored parameter, the excitation current isdecreased and, when the second predetermined set point exceeds thesecond monitored parameter, the excitation current is increased andwherein the second monitored parameter is the output power of the energyconversion device.
 20. The method of claim 19 wherein the first andsecond predetermined set points are selected to produce at least adesired degree of fuel efficiency for the prime energy source.
 21. Thelocomotive of claim 19 wherein step (i) is performed.
 22. The locomotiveof claim 19 wherein step (ii) is performed.
 23. A locomotive,comprising: a plurality of direct current traction motors incommunication with a plurality of axles; a prime energy source; anenergy conversion device, in communication with the prime energy source,to convert the energy output by the prime energy source into directcurrent electricity; an energy storage device, in communication with theenergy conversion device and the plurality of traction motors, toreceive and store the direct current electricity; a controller operableto monitor an operational parameter of each of the plurality of axlesand/or traction motors, wherein the monitored operational parameter isat least one of revolutions per minute of an axle, an electrical currentprovided to a traction motor, and a voltage applied to a component of atraction motor.
 24. The locomotive of claim 23 wherein the controller isoperable to control each of the plurality of traction motorsindependently of the other traction motors.
 25. The locomotive of claim23 wherein the controller is operable to decrease power supplied to afirst traction motor engaging a first axle without decreasing the powersupplied to other traction motors when the revolutions per minute exceeda selected threshold.
 26. The locomotive of claim 23 further comprising:an air brake assembly located on each of the plurality of axles, the airbrake assembly comprising one or more brake shoes, an air cylinder, andan fluid-activated brake release.
 27. The locomotive of claim 25wherein, when a first air brake assembly is locked in engagement with afirst braking surface on a first axle but a second air brake assembly isnot locked into engagement with a second braking surface on a secondaxle, the controller is operable to activate a first fluid-activatedbrake release on the first axle without activating a secondfluid-activated brake release on the second axle.
 28. The locomotive ofclaim 26 wherein a brake assembly is deemed to be locked when thelocomotive is in motion, the air brake assembly is deactivated, and therevolutions per minute on the axle engaging the air brake assembly areat least substantially zero.
 29. A method for controlling the operationof a locomotive, comprising: (a) providing a locomotive, the locomotivecomprising: (i) a plurality of direct current traction motors incommunication with a plurality of axles; (ii) a prime energy source;(iii) an energy conversion device, in communication with the primeenergy source, to convert the energy output by the prime energy sourceinto direct current electricity; and (iv) an energy storage device, incommunication with the energy conversion device and the plurality oftraction motors, to receive and store the direct current electricity;and (b) monitoring an operational parameter of each of the plurality ofaxles and/or traction motors, wherein the monitored operationalparameter is at least one of revolutions per minute of an axle, anelectrical current provided to a traction motor, and a voltage appliedto a component of a traction motor.
 30. The method of claim 29 furthercomprising: controlling each of the plurality of traction motorsindependently of the other traction motors.
 31. The method of claim 29further comprising: decreasing power supplied to a first traction motorengaging a first axle without decreasing the power supplied to othertraction motors when the revolutions per minute of the first axle exceeda selected threshold.
 32. The method of claim 29 wherein the locomotivecomprises an air brake assembly located on each of the plurality ofaxles, the air brake assembly comprising one or more brake pads, an aircylinder, and an air-activated brake release.
 33. The method of claim 29further comprising: when a first air brake assembly is locked inengagement with a first braking surface on a first axle but a second airbrake assembly is not locked into engagement with a second brakingsurface on a second axle, activating a first fluid-activated brakerelease on the first axle without activating a second fluid-activatedbrake release on the second axle.
 34. The locomotive of claim 33 whereina brake assembly is deemed to be locked when the locomotive is inmotion, the air brake assembly is deactivated, and the revolutions perminute on the axle engaging the air brake assembly are at leastsubstantially zero.
 35. A locomotive, comprising: a plurality of directcurrent traction motors in communication with a plurality of axles; aprime energy source; an energy conversion device, in communication withthe prime energy source, to convert the energy output by the primeenergy source into direct current electricity; an energy storage device,in communication with the energy conversion device and the plurality oftraction motors, to receive and store the direct current electricity; auser interface operable to receive a command from an operator to controla locomotive speed at a specified velocity; and a controller operable tocontrol the velocity of the locomotive at or near the specified velocityby performing at least one of the following steps: (i) maintaining asubstantially constant power across each of the plurality of tractionmotors, the power being related to the specified velocity; and (ii)maintaining the revolutions per minute of each of the plurality of axlesat a rate related to the specified velocity.
 36. The locomotive of claim35 wherein step (i) is performed.
 37. The locomotive of claim 35 whereinstep (ii) is performed.
 38. The locomotive of claim 35 whereincorresponding power applied across at least two of the traction motorsare different.
 39. The locomotive of claim 35 wherein correspondingrevolutions per minute of at least two of the axles are different.
 40. Amethod for operating a locomotive, comprising: (a) providing alocomotive, the locomotive comprising: (i) a plurality of direct currenttraction motors in communication with a plurality of axles; (ii) a primeenergy source; (iii) an energy conversion device, in communication withthe prime energy source, to convert the energy output by the primeenergy source into direct current electricity; (iv) an energy storagedevice, in communication with the energy conversion device and theplurality of traction motors, to receive and store the direct currentelectricity; and (v) a user interface operable to receive a command froman operator to control a locomotive speed at a specified velocity; and(b) controlling the velocity of the locomotive at or near the specifiedvelocity by performing at least one of the following steps: (i)maintaining a substantially constant power across each of the pluralityof traction motors, the power being related to the specified velocity;and (ii) maintaining the revolutions per minute of each of the pluralityof axles at a rate related to the specified velocity.
 41. The method ofclaim 40 wherein step (i) is performed.
 42. The method of claim 40wherein step (ii) is performed.
 43. The method of claim 40 whereincorresponding power applied across at least two of the traction motorsare different.
 44. The method of claim 40 wherein correspondingrevolutions per minute of at least two of the axles are different.
 45. Apower control system for a locomotive, comprising: a controller operableto determine an electrical current passing through each of a pluralityof direct current traction motors; and a graphical user interfaceoperable to provide the electrical current passing through each of theplurality of direct current traction motors to an operator.
 46. Thepower control system of claim 45, wherein the controller is operable toactivate an alarm when the electrical current passing through one ormore of the direct current traction motors exceeds a predeterminedthreshold.
 47. A power control method for a locomotive, comprising:determining an electrical current passing through each of a plurality ofdirect current traction motors; and providing the information of theelectrical current passing through each of the plurality of directcurrent traction motors to an operator.
 48. The power control method ofclaim 47, further comprising: activating an alarm when the electricalcurrent passing through one or more of the direct current tractionmotors exceeds a predetermined threshold.